The last decades have seen a growing interest in hash functions that allow some sort of tolerance, e.g. for the purpose of biometric authentication. Among these, the syndrome fuzzy hashing construction allows to securely store biometric data and to perform user authentication without the need of sharing any secret key. This paper analyzes such a model, showing that it offers a suitable protection against information leakage and several advantages with respect to similar solutions, like the fuzzy commitment scheme. The design and characterization of LDPC codes to be used for this purpose is also addressed.